1. Field of the Invention
The present invention relates to a semiconductor device evaluating system, and more particularly, a semiconductor device, and an apparatus and a method for manufacturing the same.
2. Description of the Related Art
Generally, as a semiconductor device has been highly integrated, it has been impossible to detect a fault in interconnect layers and circuit elements formed in a front surface of the semiconductor device. In order to effectively detect such a fault, an evaluation method such as an emission microscope (EMS) method or an optical beam induced current (OBIC) method has been developed. According to this evaluating method, infrared rays generated from the front surface penetrate the semiconductor device, so that the infrared rays can be observed from the back surface of the semiconductor device.
In a first prior art semiconductor device evaluating apparatus, if infrared rays are used for evaluating the circuits of the front surface of a semiconductor device, infrared rays are irradiated from an objective lens onto the semiconductor device, and the location of the objective lens is adjusted, so that the focal point of the infrared rays is brought close to the front surface of the semiconductor device. In this case, the wavelength of infrared rays in the semiconductor device is shorter than that in the air by the refractive index of the semiconductor device. As a result, a higher resolution can be expected by the shorter wavelength of the infrared rays in the semiconductor device. This will be explained later in detail.
In the first prior art semiconductor device evaluating apparatus, however, since the infrared rays are refracted at the back surface, the effective numerical aperture is decreased by the refractive index of the semiconductor device. As a result, the resolution increased by the shorter wavelength length is offset by the resolution decreased by the decreased numerical aperture, so that the resolution cannot be increased. In addition, since the semiconductor device is inserted into the optic axis, the aberration is increased. After all, a higher resolution cannot be realized.
In a second prior art semiconductor device evaluating apparatus (see: JP-A-5-157701), a planoconvex lens made of the same material as a semiconductor device is in direct contact with the back surface of the semiconductor device. Therefore, the combination of the planoconvex lens and a part of the semiconductor device serve as a solid immersion lens (SIL). This also will be explained later in detail.
In the second prior art semiconductor device evaluating apparatus, the infrared rays are not refracted at the convex surface of the planoconvex lens, and accordingly, the effective numerical aperture is not decreased. As a result, a higher resolution can be expected by the shorter wavelength of the infrared rays in the solid immersion lens.
In the second prior art semiconductor device evaluating apparatus, however, if a gap is generated between the planoconvex lens and the back surface of the semiconductor device, infrared rays having an incident angle larger than the critical angle are totally reflected, so that such infrared rays cannot pass through the semiconductor device. Therefore, the effective numerical aperture is limited by the critical angle.
Thus, in the second prior art semiconductor device evaluating apparatus, a higher resolution cannot be realized.
In a third prior art semiconductor device evaluating apparatus (see: S. M. Mansfield et al., xe2x80x9cSolid Immersion Microscopexe2x80x9d, Appl. Phys. Lett. 57(24), pp. 2615-2616, Dec. 10, 1990), a conical solid immersion lens is provided. This also will be explained later in detail.
In the third prior art semiconductor device evaluating apparatus, however, when evaluating the circuits of the front surface of the semiconductor device, the flat spot of the conical solid immersion lens has to be increased, and accordingly, the radius of the convex face of the conical solid immersion lens also has to be increased. Thus, the direct contact of the conical solid immersion lens may be deteriorated.
It is an object of the present invention to provide a semiconductor device suitable for a higher resolution evaluating method from the back surface thereof.
Another object is to provide an apparatus for manufacturing the above-mentioned semiconductor device.
Still another object is to provide a method for manufacturing the above-mentioned semiconductor device.
According to the present invention, in a semiconductor device having a front surface where circuits are formed and a back surface, a hemispherical solid immersion lens is formed at the back surface of the semiconductor device in a body with the semiconductor device.